1. Field of the Invention
The present invention relates to an apparatus for producing trichlorosilane and a method for producing trichlorosilane which converts silicon tetrachloride into trichlorosilane.
This application claims priority on Japanese Patent Application No. 2008-139070, filed on May 28, 2008, the content of which is incorporated herein by reference.
2. Background Art
Trichlorosilane (SiHCl3), which is used as a raw material for the production of highly pure silicon (Si), can be produced by conversion through a reaction of silicon tetrachloride (SiCl4) with hydrogen gas.
In other words, silicon is produced by the reductive reaction and the thermolysis reaction of trichlorosilane represented by reaction schemes (1) and (2) shown below, and trichlorosilane is produced by the conversion reaction represented by reaction scheme (3) shown below.SiHCl3+H2→Si+3HCl   (1)4SiHCl3→Si+3SiCl4+2H2   (2)SiCl4+H2→SiHCl3+HCl   (3)
As this apparatus for producing trichlorosilane, for example, Japanese Patent Unexamined Publication No. S62-123011 proposes an apparatus in which a plurality of heaters made of carbon are provided inside a reactor and these heaters made of carbon are directly energized and heated; thereby, heating a feed gas introduced to the reactor which contains hydrogen gas and silicon tetrachloride and converting the feed gas into trichlorosilane. In addition, a silicon compound such as silicon carbide is coated on the surface of this heater made of carbon. In other words, by protecting carbon with the coating film containing a silicon compound, the generation of impurities such as methane, methylchlorosilane, silicon carbide, and the like by the reaction of carbon with hydrogen gas, chlorosilane and hydrogen chloride in the feed gas and the reaction product gas can be prevented.
The following problems remain in the prior art described above.
That is, in the above technique disclosed in Japanese Patent Unexamined Publication No. S62-123011, silicon carbide or the like is coated on the surface of a heater made of carbon in order to prevent the generation of impurities. In this case, there were problems that the cost of the constituent members increased, and also the long-term usage of the heater could not be realized since the coating film of silicon carbide or the like was gradually etched and deteriorated.
The present invention has been made in light of these problems and an object thereof is to provide an apparatus for producing trichlorosilane and a method for producing trichlorosilane which can reduce the cost of the constituent members and which can also be configured in a way that the constituent members have a longer operating life.